10 Mar
2009
10 Mar
'09
8:56 p.m.
I've just picked up an HP120 (Z80 CP/M machine) on Ebay :-). The main
prolem (mentioned in the listing I might add, so I am not complaining) is
that it's missing the keyoard.
The keyboard connector is a 6-pin telephone type socket (RJ12?). A quick
look inside (well, what did you expect) suggests the keyboard interface
is contrlled by an 8041 microcnntroller and that it works at 12V levels
(not RS232, but 0V and +12V). There are +12V and ground pins on the
keyboard socket.
So I am looking for any/all of the following :
1) The correct HP keyoard (anyone know the model number?)
2) Details of any other keyboards that can be got to work.
3) Technical details of the keyboard interface.
-tony
12 Mar
12 Mar
1 p.m.
Tony Duell ????????:
I've just picked up an HP120 (Z80 CP/M machine) on
Ebay :-). The main
prolem (mentioned in the listing I might add, so I am not complaining) is
that it's missing the keyoard.
The keyboard connector is a 6-pin telephone type socket (RJ12?). A quick
look inside (well, what did you expect) suggests the keyboard interface
is contrlled by an 8041 microcnntroller and that it works at 12V levels
(not RS232, but 0V and +12V). There are +12V and ground pins on the
keyboard socket.
So I am looking for any/all of the following :
1) The correct HP keyoard (anyone know the model number?)
IIRC the keyboard is the same as for the HP-150A & B. I don't recall
the part number. There are two different keyboards: The original which
has sticky keys and the later update which does not. The keys usually
get stuck when pressed and won't go down. This makes it easy to break
the spacebar and other large keys, especially if one is accustomed to
typing on Teletypes and other such mechanical terminals. Silicone lube
helps but no one seems to know whether or not it will cause problems.
2) Details of any other keyboards that can be got to work.
Perhaps some other HP terminal keyboards? I do not recall any having
the same connectors and keyboard layout, though. The 150C keyboard is
not compatible.
3) Technical details of the keyboard interface.
IIRC the keyboard was sent a clock and a signal was returned when a
key was pressed. Which key was pressed was determined by timing. There
are only about 4 or 5 14 or 16 pin DIPS in the keyboard used for
scanning the matrix and sending a signal back to the MCU when a key
was pressed.
I thought it used +5VDC. My HP stuff is unreachable for the moment so
I can't check.
In case it might help, the HP150A/B tehnical manual has all the gory
details. It's part number is 45611-90002. The HP120 came out just
before the HP150 and they seem to have a lot of design in common. They
even look alike.
==
jd
Goto, n.:
A programming tool that exists to allow structured programmers
to complain about unstructured programmers.
-- Ray Simard
--
13 Mar
13 Mar
6:30 p.m.
1) The correct
HP keyoard (anyone know the model number?)
IIRC the keyboard is the same as for the HP-150A & B. I don't recall the part number. There are two different keyboards:
The original which
has sticky keys and the later update which does not. The keys usually
get stuck when pressed and won't go down. This makes it easy to break
I don't know which I have. They seem to work OK, though. The mechncial
constuction is very like an HP46020 (not 46021) keyboard.
3) Technical
details of the keyboard interface.
IIRC the keyboard was sent a clock and a signal was returned when a key was pressed. Which key was pressed was determined
by timing. There
are only about 4 or 5 14 or 16 pin DIPS in the keyboard used for
scanning the matrix and sending a signal back to the MCU when a key
was pressed.
Sure. I can understand how that works
I thought it used +5VDC. My HP stuff is unreachable for the moment so
I can't check.
Well, I might not know much about computers, but I think I can use a
votlmeter :-). More seriously, the are labelled votlage test points in
the HP120 (and I've checked them), the +12V one is wired to a pin on the
keyoard socket. And the signals to the keyboard are driven in the HP120
using 7407 drivers pulled up to the 12V line.
In case it might help, the HP150A/B tehnical manual has all the gory
details. It's part number is 45611-90002. The HP120 came out just
Do you have any idea how difficult that manual is to find? It's not on
the web AFAIK. Fortunately it is on my bookshelf (along with the HP150-II
updates). Once I relaised the HP120 interface was similar to that in the
HP150, I got a lot of clues from that manual
before the HP150 and they seem to have a lot of design
in common. They
even look alike.
Hmm.. The monitor PCB ('sweep board' in HP's terminology is, I think,
identical). The PSU is very similar (my HP150s have Panasonic PSUs, the
Hp120 has a Boschert, I am not sure if the characteristics are the same).
The logic oards are very different, of course.
The HP120 is also logically very similar to the HP125 (older CP/M machine
in the 'ET head' case (like an HP262x terminal)). The boardswapper manual
for that is on hpmuseum.net, and has some useful information in it (like
memory and I/O maps for the 2 processors).
The HP120 case is not identical to the HP150, in that the latter has a
larger top case to take the optional thermal printer. The HP150 has a
little interface circuit, mostly on the backplane PCB with a 20 pin
conenctor. There's als a 14 pin connector on the PSU board giving a 12V
supply. These are combined into a 34 wire cable that plugs into the HP2674
(IIRC) thermal printer chassis.
Now, on the HP120, the connectors are there (20 pin on the backplane, 14
pin on the PSU). Ther'es even a latch chip on the backplane to send the
data to the printer -- this chip has no other use as far as I can see.
But of course the cable isn't fitted and there;s no place to mount the
printer. Still, I am going to investiage theis further sometime.
-tony
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